"I know you can bet on anything here in Vegas, but you don't want to bet that Republicans are going to protect your healthcare," he quipped.

The former president then moved onto the economy and when he recounted Republican tax cuts, he appeared to take a not-so-subtle stab at Trump.

Clark County Commission Chairman and Democratic gubernatorial candidate Steve Sisolak, former U.S. President Barack Obama and U.S. Rep. and U.S. Senate candidate Jacky Rosen (D-NV) at the Las Vegas rally on Monday. Image: Ethan Miller/Getty Images.

"Here's just one simple fact. This is a fact! Unlike some, I actually try to state facts. I believe in facts," he offered, as the supportive crowd cheered.

"I believe in a fact-based reality and fact-based politics. I don't believe in just making stuff up. I think you should like, actually say to people what's true," he added with a smile.

The rally was focused on the state's Senate race where Democrat Jacky Rosen is challenging the Republican senator currently in office, Dean Heller.

Trump has stumped for Heller while former Vice President Joe Biden and Obama have thrown their weight behind Rosen during two separate rallies.